1. Field of the Invention
The present invention relates to an antenna and more particularly, to a small size antenna suitable for mounting inside a notebook computer for receiving broadcasting signal.
2. Description of the Related Art
Regular antennas for receiving broadcasting signal are generally of a monopole design for receiving frequency range approximately within 88˜108 MHz. In order to have a good signal receiving power, the length of a monopole antenna is set at about one fourth of signal wavelength, i.e., about 75 cm. For broad application, most monopole antennas are made in a telescopic form. A 75 cm monopole antenna is not suitable for use in a notebook computer. If a monopole antenna is made telescopic for use in a notebook computer, the notebook computer must have a hole in the shell for enabling the monopole antenna to be moved in and out of the shell of the notebook computer. However, the presence of such a hole obstructs the sense of beauty of the shell of the notebook computer.
There is known an improved structure of monopole antenna, which uses an earphone signal line for tuning. The total length of this design of monopole antenna is about one fourth of signal wavelength. However, when an external speaker is used with the notebook computer for voice output, an earphone signal line must be installed as antenna means, thereby complicated the arrangement of the outer appearance of the notebook computer. Further, because this design of monopole antenna does not have a fixed shape, it tends to produce noises.